Hollow article of refractory material.



il snares PATENT outrun.

ARTHUR T. MALM, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO NORTON COMPANY,OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

HOLLOW ARTICLE OF REFRACTORY MATERIAL.

1510 Drawing.

To all'whomitmag concern: Y

Be it known that I, ARTHUR T. MALM, a citizen of the United States,residing at Worcester, in the county of Worcester and State ofMassachusetts, have invented certain new and useful Improvements inHollow Articles of Refractory Material, of which the following is aspecification.

This invention relates to hollow articles of refractory material, suchas pyrometer tubes, combustion tubes'and the like, the object of theinvention being the provision of articles which are at the same timeimpervious to gases and capable of enduring extremely high temperatures.

The invention will be described as embodied in a pyrometer tube, but isapplicable to other articles.

Pyrometer tubes are essentially protecting media for thermo-couples,excluding injuri ous gases therefrom. They are commonly made ofporcelain, which material is however unsatisfactory in certain respects;in particular, porcelain tubes are not refractory in the now-acceptedsense of this term, inasmuch as they bend at temperatures as low as 13500.; being glazed, they are apt to adhere at high temperatures to the external support, or to any other material with which it may come incontact; they are easily broken or cracked when subjected to suddentemperature changes; and they possess a low heat-conductivity, thusintroducing a lag into the heat measurement.

Tubes made of previously molten alumina, crushed, graded and suitablybonded, present none of the above defects, being extremely refractory,free from tendency to adhere at high temperatures to contactingrefractory surfaces, able to withstand sudden temperature changeswithout injury, and possessing a thermo-conductivity so high thattemperature readings may be made without material lag. Unglazed aluminatubes are however too porous to afford suflicient protection to thethermo-couple and if the tubes are glazed they are liable to flux andadhere as is the case with porcelain tubes. According to the presentinvention, this objection is overcome by providing a pyrometer tube, orother hollow article, having an interior non- Specification of LettersPatent.

Patented Sept. 7, 1915.

Application filed October 4, 1912. Serial No. 723,865.

porous body, with a surface coating or coatings of highly refractory,unglazed and therefore porous material,usually previously moltenalumina, this material being nonglazmg. For pyrometer tubes it isadvisable to apply the unglazed coating both to the inside and outsideof the glazed tube, but for other purposes a single non-glazing coatingmay suflice this coating being usually external 1n order to avoidadherence of the highly heated tube to its refractory support.

A suitable porous composition for application to the surface or surfacesof the previously-formed and glazed tube or other artlcle may comprisepreviously molten alumlna, crushed and graded, and mixed with a smallproportion of clay or other suitable ceramic bond. This coating ispreferably applied wet, dried and fired according to the well knownmethod.

A glazed hollow article suitable for the application of the unglazedcoating may be prepared in the manner described in my Patent No.1,081,542, dated December 16, 1913.

I claim 1. A hollow article made of a highly refractory non-glazingmaterial and a glazing composition, and having a non-glazing coatingapplied thereto.

2. A hollow article comprising a highly refractory non-glazing bodyrendered impervious by a glazing composition, and having a non-glazingcoating applied thereto.

3. A hollow article comprising a highly refractory non-glazing bodyrendered impervious by a glazing composition and nonglazing exterior andinterior coatings applied thereto.

4:. A hollow article comprising a body portion containing previouslymolten alumina rendered impervious by glazing, and a non-glazing highlyrefractory coating applied to said body portion.

5. A hollow article comprising a body portion containing previouslymolten alumina rendered impervious by glazing, and non-glazing highlyrefractory exterior and interior coatings applied to said body portion.

6. A hollow article comprising a body portion containing previouslymolten alumina rior coatings containing previously molten 10 renderedimpervious by glazing, and a nonalumina applied to said body portion.glazing highly refractory coating containing In testimony whereof Iaifix my signature grelviously molten alumina applied to said inpresence of two Witnesses. 5 o y portion. v

7 A hollow article comprising a body por- ARTHUR MALM' tion containingpreviously molten alumina Witnesses:

rendered impervious by glazing, and non- ALDUS C. HIGGINS, glazinghighly refractory'exterior and inte- Ross C. PURDY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). G.

It is hereby certified that in Letters Patent No. 1,152,428, grantedSeptember 7,

1915, upon the application of Arthur T. Malm, of Worcester,Massachusetts, for an improvement in Hollow Articles of RefractoryMaterial, an error appears in the printed specification requiringcorrection as follows: Page 1, line 57, for the word unglazed readnonrglazing; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 2nd day of November, A. D., 1915.

[SEAL] R. F. WHITEHEAD,

Acting Commissioner of Patents.

